1. Field of the Invention
The present invention relates to the method and apparatus for electrically isolating two adjoining railroad rail sections together and, more particularly, to providing joined insulated rails that are machined.
2. Description of Related Art
Rail systems are often divided into sections or blocks to permit more than one train to travel on one stretch of rail. The purpose of dividing railroad rails of a rail system into sections is to detect the presence of a train on a section of rail at any given time. Each rail section is electrically isolated from all other sections so that a high electrical resistance can be measured over the rail section when no train is present in that section. When a train enters a rail section, the train will short circuit adjacent railroad rails in which the electrical resistance in the rail section drops, thereby indicating the presence of a train.
Railroad rails are generally welded to each other or attached to each other by a steel joint. Typical railroad rails generally include a body having a head section, a web section, and a base section, with the web section defining an opening for receiving fasteners. In order to electrically isolate adjacent rail sections of a rail system, high-performance, non-metallic joints or steel joints having electrically-insulated material bonded to its surface, are typically used in conjunction with electrically-insulating material placed between abutting ends of joined railroad rails. Through extended use, the wheels of the train will often cause the ends of conventional rails to deform and/or break apart (referred to in the industry as end batter), causing the railroad rails to contact each other and short out.
Certain prior art rail joint arrangements address this problem by providing two joined railroad rails that have been machine cut, tapered, and trimmed to complement each other and form a Z-shaped cut. This arrangement spreads the impact load of the train wheels over a longer area, thus increasing the Moment of Inertia at a section where the railroad rails are joined. Although the arrangement has a high Moment of Inertia, which can be defined as the capacity of a cross-section to resist bending, this arrangement utilizes non-standard railroad rails having a double-thick web section, such that non-standard rail joint bars have to be used when attaching the railroad rails to each other.